Still shows you can get it at Bike Bandit. Or you can wait(maybe a while) for one to show up on Ebay.1987 Polaris 250 Trail Boss W877527 Parts, 1987 Polaris 250 Trail Boss W877527 OEM Parts - BikeBandit.com

 

what type of oil goes into a front hub

 

First models called for type f fluid,but I'd use Polaris Demand Drive fluid in the hubs.

 

I got the front hubs finaly an check everything over. Clean fuel,clean carb, new spark. Problem is after it starts once it doesn't start again I know if it runs for about an hr it gets vapor lock but prob is runs for 5min then it won't start again after shutoff what is going on

 

Check that the gas cap vent is open along with the atmospheric vent on the carb. Plus if you didn't replace the crank seals,could be the problem and I would do a compression check also just to make sure even with a new top end.

 

its got full compression. I had the gas cap off first few times. I haven't checked crank seals the top end was rebuilt over the winter.

 

What's full compression? Plus could be a carb or fuel problem as you say or could be seals or even loss of compression as it gets warm. Several things to check. On a machine this old I would change crank seals for sure if you spent the money on a new top end. Item #6. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

it was about 120psi on compression.an if my crank seals were bad wouldn't it leak ? The only thing I forgot to check is the carb intake to see if its clogged but I blew it out with compressed air an it flowed smooth.

 

120 psi is a little on the low side if it was bored out and new piston and rings. Seals can leak especially if they're old and distorted,plus as the engine warms up seals can distort even more. Has to have good top end compression along with a good tight seal in the bottom end so the gas/oil/air mixture can atomize properly and shoot up the transfer ports to be ignited. Plus the best way to find an air leak(if you have one) is with a leak down tester.May or may not be your problem,but any leaks in seals,gaskets can cause problems.

 

its a complete original stock engine never bored out. It doesn't leak anywhere that's y I didn't think its a seal. I was told at local shop that average was 130-160psi